Thursday, August 18, 2011

Guess the Genotype #16

This dog is an Australian cattle dog (or "Queensland heeler") mixed with an Australian shepherd. The mix has produced quite a combination of genes.

First, this dog is clearly atat tan pointed. The gene is incredibly common in both breeds, so this is not surprising.

It is very possible this dog carries the liver gene. Though uncommon, the gene is present in the Australian cattle dog. It is also quite common in Australian shepherds, and I would say there is somewhere around a 50/50 chance that this dog's Australian shepherd parent was liver or carried liver. Because of this, I am going to say this dog is Bb non-liver carrying liver.

This dog is also a merle. Though at first glance this may not be obvious, but there are grey patched that must be caused by merling rather than roaning or ticking. This gene will have been inherited from the dog's Australian shepherd parent since the merle gene is not present in Australian cattle dogs. As such, this dog must be Mm merle.

As for the white on the dog, there is really only one gene that is likely to have been inherited from each parent. Australian cattle dogs are nearly fixed for the sw extreme white piebald gene. Australian shepherds are also nearly fixed for the si Irish white gene. Piebald in the sp form occurs in both breeds, but it's an infrequent occurrence, so it is unlikely to pop up. So, this dog is most likely sisw Irish carrying extreme white piebald. Because of the nature of the expression of these genes, the extreme white piebald strips away color that would normally be there (as seen in flashy boxers) and this is why the dog has a moderate piebald appearance.

This dog also shows the roaning seen in Australian cattle dogs. This is why it is a bit more difficult to distinguish the coloring. Since ticking is unusual in Australian shepherds, both the ticking gene and the roan modifier are most likely in the heterozygous form. Thus, this dog must be Tt Rr roaned.

8 comments:

Australian Shepherds are not related to Australian Cattle Dogs; they are AINO: Australian In Name Only. The Shepherd donned its name from when California imported a bunch of livestock from Australia. However some decades back, they decided to register all the dogs on the western continent as "Australian Shepherds", and the ones to the East as "English Shepherd". They really are just English Shepherds with a merle fetish.

Merle is tricky though. Sometimes they can look like a piebald when they're genetically solid. There's a good chance this one is a piebald though.

Oh, want a mind-twister? Check out the double-merles here: http://www.donabney.com/issue_merle.php. Some of the single-merles are actually homozgyous!

I thought that was mostly only true of Catahoulas? Then again, I have heard of working lines of Australian shepherds that have little to no white that have produced double merles that appear Irish white.

I think with Catahoulas, they are easier to pick on because they were originally a breed that tried to be all-merles, but it didn't work out. However they're unwilling to lose the iconic image of the merle cur, so there are still a lot of double-merles and single-merles floating around.

The Shetland people tried to do the same thing; and so did the Dunkerhound people as well.

Chris, that is very interesting! I wonder what it could be. It's possible it's mosaicism, chimerism, or just an unusual facial patch. In the past I have seen a greyhound with a mostly white head that had a patch at the end of its muzzle, but it was nowhere near as big.